Method for the examination or inspection of rotogravure printing cylinders or the like

Claim 1

A method of examining cells formed in the surface of a rotogravure cylinder, particularly for use in the preparation of rotogravure cylinders by etching, in which method cells are formed in at least two regions of the surface of said material layer which cells each have one of their side walls or a portion of one of their side walls extending under the same angle relative to the surface of said material layer, whereby all of these side walls or side wall portions extend parallel to each other and whereby all of the cells of any region each have identical depths but the cells of adjacent regions have different depths, said method comprising: scanning said regions individually and successively with a bundle of ultrasonic beams which are projected onto the surface of said material layer, in a plane perpendicular to said side walls or side wall portions and at an angle theta with said surface, measuring the intensity of the partial bundle reflected from the bottom and from said wall or wall portion of each cell of the respectively scanned region and extending parallel to the incident beam and ignoring the beams reflected from all other flat surfaces, and producing a signal corresponding to the actual depth of said cells, scanning a drum provided with a pattern by means of a scanning element in such a manner that the area scanned on the pattern with respect to area and position corresponds to the area sensed by said ultrasonic scanner on the rotogravure cylinder and producing a signal representative of the desired cell depth; comparing the signals representing actual cell depth and desired cell depth with each other in a signal difference analyzer such that the difference output formed by said analyzer is substantially zero when the cells of said rotogravure cylinder scanned by said ultrasonic scanner provide a signal corresponding to the reference value of the pattern produced by said scanning element, while the difference is unequal to zero when the signal produced by said ultrasonic scanner does not correspond to said reference value, and the cells are engraved too deep or too shallow in comparison with the value established by said pattern, and activating a monitor means when the difference formed by said analyzer is unequal to zero.

Claim 2

A method of examining cells formed in the surface of a rotogravure cylinder, particularly for use in the preparation of rotogravure cylinders by etching, in which method cells are formed in at least two regions of the surface of said material layer which cells each have one of their side walls or a portion of one of their side walls extending under the same angle relative to the surface of said material layer, whereby all of these side walls or side wall portions extend parallel to each other and whereby all of the cells of any region each have identical depths but the cells of adjacent regions have different depths, said method comprising: scanning said regions individually and successively with a bundle of ultrasonic beams which are projected onto the surface of said material layer, in a plane perpendicular to said side walls or side wall portions and at an angle theta with said surface, measuring the intensity of the partial bundle reflected from the bottom and from said wall or wall portion of each cell of the respectively scanned region and extending parallel to the incident beam and ignoring the beams reflected from all other flat surfaces, and producing a signal corresponding to the actual depth of said cells, scanning a drum provided with a pattern by means of a scanning element in such a manner that the area scanned on the pattern with respect to area and position corresponds to the area sensed by said ultrasonic scanner on the rotogravure cylinder and producing a signal representative of the desired cell depth; comparing the signals representing actual cell depth and desired cell depth with each other in a signal difference analyzer such that the difference output formed by said analyzer is substantially zero when the cells of said rotogravure cylinder scanned by said ultrasonic scanner provide a signal corresponding to the reference value of the pattern produced by said scanning element, while the difference is unequal to zero when the signal produced by said ultrasonic scanner does not correspond to said reference value, and the cells are engraved too deep or too shallow in comparison with the value established by said pattern, and activating a monitor means when the difference formed by said analyzer is unequal to zero.

Claim 9

A method for monitoring the depth of cells formed with parallel cell walls in the surface of a rotogravure cylinder and for signifying those cells which are of an improper depth, said method comprising the steps of: scanning the rotogravure cylinder with an incident ultrasonic beam projected onto the cylinder surface in a plane substantially perpendicular to said cell walls; measuring the intensity of the portion of said incident beam which is reflected backwardly substantially along and parallel to the incident beam and producing therefrom a first signal representative of the actual depth of the cells then being scanned, scanning a reference pattern having sensible characteristics thereover representative of desired cell depths for respectively corresponding areas of the rotogravure cylinder and producing a second signal corresponding thereto, synchronously comparing said first and second signals to produce a first output signal if the actual cell depth is substantially greater than the desired cell depth and a second output signal if the actual cell depth is substantially less than the desired cell depth, and indicating said first and second output signals in association with respectively corresponding areas of the rotogravure cylinder thereby enabling corrective action.

Claim 10

A method for monitoring the depth of cells formed with parallel cell walls in the surface of a rotogravure cylinder and for signifying those cells which are of an improper depth, said method comprising the steps of: scanning the rotogravure cylinder with an incident ultrasonic beam projected onto the cylinder surface in a plane substantially perpendicular to said cell walls; measuring the intensity of the portion of said incident beam which is reflected backwardly substantially along and parallel to the incident beam and producing therefrom a first signal representative of the actual depth of the cells then being scanned, scanning a reference pattern having sensible characteristics thereover representative of desired cell depths for respectively corresponding areas of the rotogravure cylinder and producing a second signal corresponding thereto, synchronously comparing said first and second signals to produce a first output signal if the actual cell depth is substantially greater than the desired cell depth and a second output signal if the actual cell depth is substantially less than the desired cell depth, and indicating said first and second output signals in association with respectively corresponding areas of the rotogravure cylinder thereby enabling corrective action.